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Homework 3

Assigned Feb 18, due Feb 27

Pair Programming

You are encouraged to do this assignment in a two-student team, following the principles of Pair Programming. This does not mean "you do these problems and I'll do those"; it means both students work together, looking over one another's shoulders, to complete all the problems. Turn in one copy with both names on it. I recommend that you choose a different partner for the next homework assignment, so if you don't get along with this partner, remember it's only for a week :-)

Problems

You are to write six animations. Some will require defining only one new function; some may require two or three. To complete these in ten days, you need to write at least one function a day.

Chapter 6: Animations and games

• Warm-up (not graded): Try all of the "Worked Exercises" and "Practice Exercises" as you get to them: either type them in from the book, or download them from here, then run them and make sure they do what you expect.
• Exercise 6.4.4
• Exercise 6.5.2
• One of Exercises 6.5.4, 6.5.5, 6.5.6. (Some older printings of the book don't have exercises 6.5.5 and 6.5.6, but the on-line version does.)
• Exercise 6.7.1
• Make up an interesting animation of your own, involving a tick handler, a draw handler, and either a mouse or a keyboard handler (or both). Go wild. (You may want to try exercises 6.7.2 or 6.7.3 as a warm-up, but don't turn them in.)

What to turn in and how

When you define a function, I want to see all the steps of the recipe, except that in the course of writing a function body, you normally replace the "..." that was in the function skeleton.

An animation may require writing one, two, or more new functions; once all these functions work correctly on their own, you should write a big-bang call in the Definitions pane to actually run the animation.

I recommend putting all of the programming problems in one big Definitions pane, because some of them depend on others.

Send me an e-mail, attaching the file containing your saved Definitions pane. (Make sure to save it, then test it, then e-mail it to me, or I may end up grading an out-of-date version.) Make sure to put your name in the Subject line!

If there's a particular function that you can't get working, turn in as many steps of the recipe as you've managed to do, commented out (so they don't mess up the other functions).

Also turn in a log of how many errors of different kinds you encountered in the assignment, with brief comments describing each one ("mismatched parentheses" is self-explanatory, but more complex errors might need more description). Note that "errors" means not only error messages from DrScheme, but also wrong answers. You may do this using the PSP forms, or simply by keeping track in a text file or on paper and turning it in.

Grading standards

In order to get you feedback quickly, I won't actually grade all of these problems; the rest should be considered practice.

Error log:       25 points
(I'm not grading on how many or how few errors you encountered, only on whether you recorded them correctly.)

The table below has columns for each step in the design recipe, and a row for each function that I decide to grade. You won't turn in a separate skeleton, inventory, and body, but rather write a skeleton and then add inventory and body to turn it into a complete definition. However, if you don't get the definition working, you'll still get partial credit for a correct contract, skeleton, and/or inventory.

General skills:

Total:         /???